What is the presentation and diagnostic workup for Bell's (Idiopathic Facial Paralysis) palsy?

From the Guidelines

Bell's palsy presents as an acute onset of unilateral facial weakness or paralysis affecting all branches of the facial nerve (CN VII), and the diagnostic workup begins with a thorough history and physical examination to exclude identifiable causes of facial paresis or paralysis, as recommended by the clinical practice guideline 1. The diagnostic workup for Bell's palsy should focus on the timing of symptom onset, presence of pain, and complete neurological assessment to rule out other causes of facial weakness.

• No specific laboratory tests are required for diagnosis, as Bell's palsy is primarily a clinical diagnosis of exclusion, according to the guideline 1.
• Imaging is generally unnecessary in straightforward cases but may include MRI if there are atypical features or concern for alternative diagnoses.
• The guideline strongly recommends that clinicians should assess the patient using history and physical examination to exclude identifiable causes of facial paresis or paralysis in patients presenting with acute-onset unilateral facial paresis or paralysis 1.
• Clinicians should not obtain routine laboratory testing in patients with new-onset Bell’s palsy, as stated in the guideline 1.
• Clinicians should not routinely perform diagnostic imaging for patients with new-onset Bell’s palsy, unless there are atypical features or concern for alternative diagnoses, as recommended by the guideline 1.
• Treatment should be initiated promptly with oral steroids within 72 hours of symptom onset for Bell’s palsy patients 16 years and older, as strongly recommended by the guideline 1.
• Antiviral therapy with valacyclovir may be added, particularly in cases with severe paralysis, though evidence for its benefit is less robust than for steroids, as noted in the guideline 1.
• Eye protection is crucial for patients unable to close their affected eye; artificial tears during the day and lubricating ointment with eye patching at night are recommended to prevent corneal damage, as stated in the guideline 1.
• Most patients (about 85%) recover completely within 3 months, but those with complete paralysis, older age, or hypertension may have a less favorable prognosis, according to the guideline 1.
• Referral to a neurologist is warranted if symptoms worsen despite treatment, fail to improve after 3 weeks, or if there are atypical features suggesting an alternative diagnosis, as recommended by the guideline 1.

From the Research

Presentation of Bell's Palsy

• Bell's palsy is a peripheral palsy of the facial nerve that results in muscle weakness on one side of the face 2
• Affected patients develop unilateral facial paralysis over one to three days with forehead involvement and no other neurologic abnormalities 2
• Symptoms typically peak in the first week and then gradually resolve over three weeks to three months 2
• Bell's palsy is more common in patients with diabetes, and although it can affect persons of any age, incidence peaks in the 40s 2

Diagnostic Workup

• The diagnosis of Bell's palsy is based on exclusion, and a thorough history and physical examination are essential 3
• Laboratory evaluation, when indicated by history or risk factors, may include testing for diabetes mellitus and Lyme disease 2
• Electromyography-electroneurography, and brain CT-scan may be carried out after 15 days and 21 days respectively of treatment, if neurological deficit is unchanged 4

Complications and Prognosis

• A common short-term complication of Bell's palsy is incomplete eyelid closure with resultant dry eye 2
• A less common long-term complication is permanent facial weakness with muscle contractures 2
• Approximately 70 to 80 percent of patients will recover spontaneously 2
• Treatment with a seven-day course of acyclovir or valacyclovir and a tapering course of prednisone, initiated within three days of the onset of symptoms, is recommended to reduce the time to full recovery and increase the likelihood of complete recuperation 2, 5

Treatment Options

• Corticosteroids are the mainstay of treatment and should be initiated within 72 hours of symptom onset 3
• Antiviral therapy in combination with corticosteroid therapy may confer a small benefit and may be offered on the basis of shared decision making 3
• Physical therapy appears to be effective only in the more severe Bell's palsy (baseline HB grade V/VI), whereas less severe Bell's palsy (baseline HB grade IV) results in complete spontaneous recovery, regardless of physical therapy 6